Interlocking system for railroad s



March 15, 1938. s. N. WIGHT INTERLOCKING SYSTEM FOR RAILROADS Filed Oct. 16, 1954 ATTORNEY E HJ UH Patented Mar. 15, 1938 UNITED SATES 2,lll,5

AT E

orFics INTERLOCKING SYSTEM FOR RAILROADS Application October 16, 1934, Serial No. 748,481

8 Claims.

This invention relates to interlocking systems for railroads and it more particularly pertains to a system in which the interlocking is accomplished by electrical isolation.

In interlocking traffic controlling devices in an interlocking system it is necessary to so interlock the various traffic controlling devices that conflicting routes cannot be set up.

The present invention is particularly applicable to a railroad crossing with provision of route circuit portions which conform with the various portions of the track layout, so organized that the clearing of signals for particular directions of traffic over the route represented by the route circuit is effective to prevent the clearing of signals for trafiic in a conflicting direction.

More specifically, one route relay circuit is employed to control both routes over a railway crossing and means are provided in connection with the signal clearing circuits requiring all signals to be at stop before a given signal can be cleared. Interlocking of the signal clearing relays is such that only one signal can be cleared at any one time.

The present invention is shown applied to a railway crossing having no switches. An important feature of the invention is the application of the route relay principle disclosed in my prior application Ser. No. 540,596, filed May 28, 1931, to such a railway crossing. In this connection it will be apparent that the invention may be applied to a track layout of the form illustrated in Fig. 2, that is, the crossing signals may be controlled as specifically illustrated in Fig. l with the signals for the turnouts, cross-overs, and the like, of each railroad interlocked with the asso ciated switches in agrouping arrangement such, for example, as shown in the prior application of A. Langdon, Ser. No. 739,977, filed August 15, 1934.

' Apparatus The track layout of Fig. 1 includes a railroad crossing which, for convenience in describing the present invention, is referred to as section l-Z which crosses section 3-4.

The signalling arrangement provided as a typical example comprises signal IS for governing West bound trafiic over section IZ, signal 28 for governing east bound traffic over section |2, signal 35 for governing west bound trafiic over section 34 and signal is for governing east bound traffic over section 3--4. These signals are illustrated as being of the color light signal type although they may be of any other suitable type governed in accordance with the present invention by associated lever repeating relays IGZ, ZGZ, 3G2 and lGZ.

The condition of occupancy of the various track sections is preferably repeated in the tower by track relays or track repeating relays, but for convenience in describing the invention applied to the track layout of Fig. 1 the detailed circuits of such relays have been omitted from the drawing. Such track sections into which the track is divided by suitable insulated joints are assumed to have track circuits of the usual closed circuit type. While the detailed track relay circuits are not shown, relay T is the normally energized track relay for the section of track comprising the crossing. Relays T20, T40, T39 and Till are the normally energized track relays for the approach sections adjacent to sections 2, 4, 3 and l respectively.

Relays G are associated with their respective signals as designated by the numerals preceding their letter reference characters. Each of these relays when deenergized causes its associated signal to indicate stop but when energized causes its associated signal to indicate proceed, sub ject to traific conditions in accordance with the usual practice.

Relays GZ are associated with their respective signal levers as designated by the numerals preceding their letter reference characters. Levers SGL (with suitable preceding numerals) govern the corresponding signals subject to the interlocking operation as will be pointed out in detail later.

A time element thermal relay TR and an associated stick relay S are shown cooperating with signal relays G to control signal controlling relays GZ for delaying the clearing of a signal for a predetermined time after signals are restored to stop;

Operation Normal conditions.--The signal control levers are usually returned to normal at stop positions as shown in Fig. 1 so that the respective signals display stop indications. More specifically, the red lamp of signal IS for instance is energized over a circuit extending from back contact It of relay IG and the red lampoi sig nal IS, to A similar circuit is effective for lighting the red lamp of signal 28 extending from through back contact 22 of relay 2G. A similar circuit is effective for lighting the red lamp or signal 33 extending through back contact lZof relay 3G. A similar circuit is effective for lighting the red lamp of signal 4S extending through back contact I3 of relay 4G.

With the track sections unoccupied, the track relays are normally energized but since the detailed circuit arrangement for maintaining these relays energized is familiar to those skilled in the art it is believed unnecessary to show these detailed track circuits.

With the signal control levers in their at stop positions, the time element stick relay is energized over a circuit extending from winding of relay S, front contact I4 of relay S, heating element I5 of relay TR, back contacts I6, I'I, I8 and I9 of relays 3G, IG, 4G and 2G respectively, to With track relays T20, T40, T and TIO all picked up a shunt circuit is completed around front contact I4 of relay S which extends through normally closed front contacts 2|, M, 3I and II of these respective T relays.

Signal controZ.--An explanation will now be given of the individual control of the signals by their respective levers, subject to route control and time looking, which features will be described later in the specification.

For example, assuming the system to be in its normal condition as illustrated, the actuation of lever ISGL to its clear position closes a circuit for picking up relay I G2 which extends from contact of lever ISGL in its right hand dotted position, back contact 23 of relay 3G2, winding of relay IGZ, back contact 2 1 of relay I3RR, conductor 50, front contact 25 of relay S, contact 26 of relay TR in its left hand position, back contacts IS, IT, I8 and I9 of relays 3G, IG, 3G and" 2G respectively, to The response of relay IGZ completes its stick circuit including front contact 21", thereby rendering relay IGZ wholly dependent upon the lever ISGL in the event that route relay I3RR, is picked up in response to the energization of relay IGZ, provided the route is established and proper to be cleared as will now be described.

Relay I3RR is energized over a circuit extending from back contact 28 of relay ZGZ,

back contact 29 of relay 4GZ, windings of relays 24RR and ISRR in series and front contact 32 of relay IGZ, to Both relays I3RR and 24RR are picked up over this circuit Relay IG is energized over a circuit extending from front contact 33 of relay T, front contact 34 of relay I3RR, front contact 35 of relay IGZ and winding. of relay IG, to The picking up of relay IG opens the stick circuit of relay S at back contact I"! and at contact I0 switches the energizing circuit from the red to the green lamp of signal IS, thereby causing signal IS to give a proceed indication.

From the above it is apparent that the operation of a signal lever so conditions the route circuits that the signal will be cleared which is associated with the operated signal lever if it is proper for such signal to be cleared. This conditioning of the route circuit also prevents opposing signal levers from being effective, since the picking up of the route relay 24RR prevents the picking up of either relay ZGZ or lGZ. The picking up of relay I3RR also prevents the energization of relay 3GZ, all of which is effective to prevent the clearing of conflicting signals.

This part of the description more particularly points out how a particular signal lever func tions to condition a route circuit and how the response of such route circuit governs the response of the associated signal. The pick up and stick circuits for each GZ relay and the energizing circuit for each G relay will now be pointed out.

The pick up circuit for relay ZGZ extends from contact of lever ZSGL in its right hand dotted position, winding of relay 2G2, back contacts 36 and 3'! of relays GGZ and 24RR in series, conductor 59, front contact 25 of relay S, contact 26 of relay TR in its left hand position, back contact I6, I'I, I8 and I9 of relays 3G, IG, 4G and 2G respectively, to The stick circuit for relay ZGZ is completed through its front contact 38.

The picking up of relay 2GZ closes a circuit for picking up route relays RR and I3RR in series extending from back contact 39 of relay 3GZ, back contact 32 of relay IGZ, windings of relays I3RR and 24RR in series, back contact 29 of relay 4GZ and front contact 28 of relay ZGZ, to

A circuit is closed for picking up relay 26 which extends from front contact 33 of relay T, front contact 32 of relay NRR, front contact 43 of relay ZGZ, and winding of relay 2G, to When relay 2G is picked up, the switching of contact 22 removes the stop indication of signal 2 and establishes its proceed indication.

The pick up circuit for relay 3G2 extends from contact of lever 3SGL in its right hand dotted position, winding of relay 3GZ, back contacts 4 and 45 of relays K32 and I3RR in series, conductor 5!! and over the remainder of the previously described circuit, to at back contact I 9 of relay 2G. Relay 3GZ establishes its stick circuit at its front contact 46.

The'picking up of relay SGZ' closes a circuit for picking up relays I3RR and MRR in series which extends from back contacts 28 and 29 of relays ZGZ and lGZ respectively, windings of relays MRR and I3RR, back contact 32 of relay IGZ and front contact 39 of relay 3G2, to

Relay 3G is picked up over a circuit extending from front contact 33 of relay T, front contact 34 of relay I3RR, front. contact 4'! of relay 3GZ and winding of relay 3G, to The switching of contact I2 of relay 3G deenergizes the red indicator of signal 3S and energizes the green or proceed indicator of this signal.

The pick up circuit of relay 4GZ extends from contact of lever ISGL in its right hand dotted position, back contact 48 of relay ZGZ, winding of relay 4G2, back contact 49 of relay 24RR, conductor 50 and over the previously described circuit, to at back contact IQ of relay 2G. Relay AGZ establishes its stick circuit at its front contact 5|.

The picking up of relay AGZ closes a circuit for picking up relays 24RR and I3RR in series which extends from, back contacts 39 and 32 of relays 3GZ and IGZ respectively, windings of relays I 3RR and 24RR and front contact 29 of relay 4GZ, to

Relay 4G is energized over a circuit extending from front contact 33 of relay T, front contact 42 of relay 24RR, front contact 52 of relay 4GZ and winding of relay 4G, to The switching of contact I3 of relay AG changes the indication of signal 48 from red to green.

The above description points out the detailed circuits for clearing any one of the four signals illustrated. It will be apparent that a signal can only be cleared when all signals are at stop, because the pick up circuits for the GZ relays include conductor 50 which is deenergized by the opening of some one of the contacts l6, ll, [8 and I9 when any signal is cleared. It will also be apparent that only one signal of the group can be cleared at any one time, since the picking'up of a G relay opens the above described pickup circuit for the GZ relays. In addition to this, relays IGZ and 3GZ are interlocked with each other, that is, the picking up of either one of these relays opens the pick up circuit of the other. Similarly, relays 2G2 and M32 are interlocked with each other since the opening of back contact 48 of relay ZGZ opens the pick up circult of relay 1G2 and the opening of back contact 36 of relay dGZ opens the pick up circuit of relay ZGZ. Furthermore, when a route circuit has been established by the picking up of the route relays Z lRR. and I3RR in response to the pickingup of the G2 relay, the pick up circuits of all GZ relays are opened at back contacts 24, 3'5, 45 and 49 of the RR relays. The only GZ relay energized is the on e that was picked up to establish its above described stick circuit.

- Time release-In order to allow sufficient time for a train approaching a signal to stop after such signal has been restored to a-stop condition before another signal can be cleared, a time release feature has been provided.

Upon the picking up of any one of the G relays, the energizing circuit of relay S is opened allowing this relay to drop away. Then upon the clo sure of the back contact of the G relay (upon its release for restoring the associated signal to stop), energy-is applied to the thermal relay TR over a circuit extending from back contact 14 of relay S, heating element I5 of relay TB, back contacts l6, ll, l8 andlQ of relays 3G, lG, 4G and 2G respectively, to The current flowing in this circuit causes the thermal relay to close its right hand contact 26 after a predetermined time, which is effective to pick up relay S over a circuit extending from winding of relay S, right hand contact of relay TR, back contacts iii, ll, l8 and i9 of relays 3G, IG, 4G and 2G respectively, to The picking up of relay S opens the direct circuit to at its back contact M which deenergizes thermal relay TR. Relay TR slowly shifts its contact 26 from the right to the left and relay S maintains itself energized over the above described stick circuit including the heating element of relay TR, but since the resistance of the winding of relay S is high, the value of the current which flows through heating element i5 is not sufficient to prevent this relay restoring to normal.

As soon as contact 26 is closed in its left hand position, conductor 5!! is supplied with potential so that a GZ relay may be energized in responseto its lever movements. From this it is seen that the response of a G relay to clear a signal, followed by the restoration of the associated signal lever to normal (which puts this signal to stop) causes a predetermined time to be measured oil by relay TR before this or any other signal can be cleared.

Such an arrangement serves to prevent the quick reversal of trafiic direction or the quick shifting of clear signals forconflicting routes by the quick manipulation of the signal levers, thereby giving adequate protection to the movement of trains over the track section illustrated.

Front contacts 2!, M, 3i and H of relays T20, T lt, T and TH! respectively are shown connected to the time element circuit in such a way that the time delay in clearing a subsequent signal as above described is eliminated. In the event that there is no train in any of the sections adjacent to the illustrated section, then it is unnecessary to include this delayed action in the operation of the signals.

With all of these adjacent track sections unoccupied relays T20, T40, T30 and TIE will be picked up so that when a cleared signal is restored to its stop condition, a circuit for immediately picking up relay S is effective which extends from winding of relay S, front contacts H, 3|, 4, and 2| of relays Till, T30, T40 and T20 respectively, back contacts I 6, l1, l8 and I9 of relays 3G, IG, 4G and 2G respectively, to Since relay S is immediately picked up under the above condition, the removal of from the heating element of relay TR at back contact it of relay S prevents the operation of relay TR and therefore the circuit for the G2 relays is retained intact at contact 26 in its left hand position.

Having thus described an interlocking system as one specific embodiment of the present invention it is to be understood that various modifications, adaptations and alterations may be applied to meet the requirements of practice without in any manner departing from the spirit or scope of the invention except as limited by the appended claims.

stretches of track in both directions an individual control lever for each of said signals for clearing the associated signal, interlocking means,

allowing only one of said signals to be cleared at any one time, and a single delay means for all of the signals allowing each signal to be cleared onlya predetermined time after one of said signals has been put to stop.

2. In a trafiic controlling system for railroads, a first stretch of track, a second stretch of track intersecting said first stretch of track, a third stretch of track adjacent one of the other stretches of track, a track relay controlled over said third stretch of track, signals governing the entrance of traflic into said first and second stretches of track in both directions, an individual control lever for each of said signals for clearing the associated signal, interlocking means allowing only one of said signals to be cleared at any one time, a single delay means allowing each signal to be cleared only a predetermined time after one of said signals has been put to stop, and means controlled by said track relay for disabling said delay means.

3. In a traffic controlling system for railroads, a first stretch of track, a second stretch of track intersecting said first stretch of track, signals governing the entrance of trafiic into said stretches of track in both directions, a signal control lever for each of said signals and having clear and stop positions, means associated with each of said levers and its respective signal for clearing said signal when its associated lever is in its clear position, interlocking means allowing only one of said signals to be cleared at any one time, and a single means for automatically delaying the clearing of any of said signals for an appreciable time after one of said signals has been restored fro-m a clear to a stop condition.

4. In an interlocking system for railroads, a pair of intersecting track sections, signals governing trafiic both ways over said sections, levers corresponding to said signals, a route control circult comprising means for controlling said signals, means responsive to the actuation of one of said levers to its clear position for energizing said route control circuit only when all other levers are in their stop positions, means responsive tothe energization of said route control circult for clearing the signal corresponding to the actuated lever, and a single means for automatically delaying the clearing of any of said signals for a predetermined time after one of said signals has been restored from a clear to a stop condition.

5. In a railroad crossing, two stretches of track crossing each other, a signal at the entrance of each end of each stretch, a signal relay to control each signal, a manually operable lever for controlling each signal, a lever relay for each lever, a route circuit energized upon the picking up of one and only one of the lever relays, each signal relay having an energizing circuit requiring, for its energization, that the route circuit be energized and a front point of the corresponding lever relay be closed, each lever relay having a pick-up circuit including a back point of each of the signal relays.

6. In a railroad crossing, two stretches of track crossing each other, a signal at the entrance of each end of each stretch, a signal relay to control each signal, a manually operable lever for controlling each signal, a lever relay for each lever, a route circuit energized upon the picking up of one and only one of the lever relays, each signal relay having an energizing circuit requiring, for its energization, that the route circuit be energized and a front point of the corresponding lever relay be closed, each lever relay having a pick-up circuit including a back point of each of the signal relays, and the back point of another lever relay and requiring for its energization that the route circuit be de-energized.

'7. In a railroad crossing, two stretches of track crossing each other, a signal at the entrance of each end of each stretch, a signal relay to control each signal, a manually operable lever for controlling each signal, a lever relay for each lever, a route circuit energized upon the picking up of one and only one of the lever relays, each signal relay having an energizing circuit requiring, for its energization, that the route circuit be energized and a front point of the corresponding lever relay be closed, each lever relay having a pick-up circuit including a back point of each of the signal relays, the energizing pick-up circult for each lever relay including a time contact opened upon the clearing of a signal and time measuring means for causing the time contact to close upon putting the signal to stop only after the elapse of a predetermined time.

8. In a railroad crossing, two stretches of track g crossing each other, a signal at the entrance of each end of each stretch, a signal relay to control each signal, a manually operable lever for controlling each signal, a lever relay for each lever, a route circuit energized upon the picking up of one and only one of the lever relays, each signal relay having an energizing circuit requiring, for its energization, that the route circuit be energized and a front point of the corresponding lever relay be closed, each lever relay having a pick-up circuit including a back point of each of the signal relays, and the back point of another lever relay requiring for its energization that the route circuit be de-energized, the energizing pickup circuit for each lever relay including a time contact opened upon the clearing of a signal and time measuring meansrfor causing the time contact to close upon putting the signal to stop only after the elapse of a predetermined time.

SEDGWICK N. WIGHT. 

